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V.R. Metaphysical Aesthetics


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#101 Saiph

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Posted Jul 24 2018 - 06:19 PM

View PostJohn Woods, on Jul 23 2018 - 08:07 AM, said:

..... the difference between the direction the tire is heading and the direction it is pointing.....

That's it. You've got it.

#102 John Woods

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Posted Jul 25 2018 - 07:39 AM

Onward thru the fog...

Bunch of math by Josh the Engineer, wild guess cartoon of Hill trying to drive like Jimmy, page from DJ's book about how to drive a race car.


:D

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Edited by John Woods, Jul 25 2018 - 08:49 PM.


#103 gliebzeit

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Posted Jul 25 2018 - 08:22 AM

View PostSaiph, on Jul 24 2018 - 06:19 PM, said:

View PostJohn Woods, on Jul 23 2018 - 08:07 AM, said:

..... the difference between the direction the tire is heading and the direction it is pointing.....

That's it. You've got it.

Yes, that is it !!  :thumbup:
My words were poorly chosen, before.

#104 John Woods

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Posted Jul 27 2018 - 01:45 PM

Would agree its a weird kind of fun staring at a seven word sentence for half a day wondering whether it makes any sense at all, carries a topic forward, and most important, if its even really what you want to say.

The whole point tho is to say something.
Appreciate that when others do.
:)

Pretty sure there are five slip angles, (four tires and car's center of mass), whose respective forces altogether establish a summative trajectory.
Due to each angle being on its own, effected by unique circumstance, at any time they can all be different.
Might not be what you want at that moment.

In general old school big slip drivers preferred more slip on rear (oversteer) than the front (understeer).
According to a reliable source, they would get a little more understeer dialed in for big tracks like Spa and have cars set up with a little more oversteer for twisty circuits like the Ring.



:D

Edited by John Woods, Jul 27 2018 - 06:36 PM.


#105 Remco Hitman

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Posted Jul 27 2018 - 08:20 PM

No and no. The chassis doesn't have a slip angle, that term is reserved for rubber. What you're thinking of is yaw.
There is a slip angle per tyre. Toe settings have a permanent effect on slip angle.

Also, slip angle does not equate to under- or oversteer. Some slip angle is required to push the fronts around the turn, in which case there is no understeer (yet).

#106 John Woods

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Posted Jul 27 2018 - 08:44 PM

Okay, four slip angle vectors and the sideslip angle?
(Learned something new).

"Typical active safety systems that control the dynamics of passenger cars rely on the real-time monitoring of the vehicle sideslip angle (VSA), together with other signals such as the wheel angular velocities, steering angle, lateral acceleration, and the rate of rotation about the vertical axis, which is known as the yaw rate. The VSA (also known as the attitude or “drifting” angle) is defined as the angle between the vehicle’s longitudinal axis and the direction of travel, taking the centre of gravity as a reference. It is basically a measure of the misalignment between vehicle orientation and trajectory; therefore, it is a vital piece of information enabling directional stability assessment, such as in transience following emergency manoeuvres, for instance."

From:(PDF) On the Vehicle Sideslip Angle Estimation:.... Available from: https://www.research...and_Innovations [accessed Jul 27 2018].

Attachments found after a few minutes search for images.


:D

Attached Files


Edited by John Woods, Jul 27 2018 - 09:21 PM.


#107 Remco Hitman

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Posted Jul 27 2018 - 09:23 PM

A slip angle is not a vector as it does not indicate a force. Your image is wrong for oversteer. Both are drawn as understeer by looking at the fronts.

#108 John Woods

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Posted Jul 27 2018 - 09:28 PM

You are up too late.
:P

What is that slip angle arrow telling us?


:D

#109 Remco Hitman

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Posted Jul 27 2018 - 09:30 PM

I'm in Florida :-)

#110 John Woods

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Posted Jul 27 2018 - 09:36 PM

:D

Well, wish we could visit now that we're only 1,000 miles away.

Anything more to tell like why you're here, what you're doing?

This is from Wikipedia btw:
"slip angle or sideslip angle is the angle between a rolling wheel's actual direction of travel and the direction towards which it is pointing (i.e., the angle of the vector sum of wheel forward velocity v_x and lateral velocity v_y)"

Edited by John Woods, Jul 27 2018 - 09:50 PM.


#111 Remco Hitman

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Posted Jul 27 2018 - 09:52 PM

Summer holiday with my family; Miami atm, Key West next. Bartow next week (with visits to Sebring and Kennedy Space Center), then back down the West coast to Sanibel. Life is good to us ;)

#112 John Woods

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Posted Jul 27 2018 - 09:55 PM

Going all over!
Fantastic.
Everyone loves Sanibel.

All the best.


:D

#113 Remco Hitman

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Posted Jul 27 2018 - 09:58 PM

Yes, the angle of the vector sum, but no vector itself (vector indicating direction, point of origin and magnitude).

Kind of like being Assistent to the Regional Manager, but not Assistent Regional Manager (The Office US reference).

#114 gliebzeit

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Posted Jul 28 2018 - 08:33 AM

:cool:

Attached File  Falcon 9.jpg   61.79K   16 downloads  Attached File  Delta 4.jpg   73.56K   16 downloads

:D

Edited by gliebzeit, Jul 28 2018 - 08:36 AM.


#115 John Woods

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Posted Jul 28 2018 - 10:05 AM

Just having fun...

The Sum of Two Vectors
From: revisionworld.com/a2-level-level-revision/physics/force-motion/forces-vectors/sum-two-vectors


"The sum, or resultant, of two vectors such as two forces acting on a single object is the single vector that could replace the two and have the same effect.

There are three steps to finding the sum of two vectors. These are illustrated by working out the sum of a 2 N force acting up the page and a 3 N force acting from left to right, both forces acting on the same object.

Draw an arrow that represents one of the vectors in both size and direction.
Starting where this arrow finishes, draw an arrow that represents the second vector in size and direction.
The sum, or resultant of the two vectors is represented (in both size and direction) by the single arrow drawn from the start of the first arrow to the finish of the second arrow.

In the example given, the size of the resultant force is 3.6 N and the direction is at an angle of 34° to the 3 N force. These figures were obtained by scale drawing."

(The example is shown in the attachment, appears very similar to slip angle diagram)

Unit Vectors | Brilliant Math & Science Wiki
From: brilliant.org/wiki/unit-vectors

"Vector quantities have a direction and a magnitude. However, sometimes one is interested in only the direction of the vector and not the magnitude. In such cases, for convenience, vectors are often "normalized" to be of unit length."

Plus, an arrow is universally used to diagram a vector.

Note in the first definition use of the words "could replace."
Could this be changed to "in the case of tire slip does replace the two and has the same effect, as demonstrated by new line of travel and by sidewall and tread distortion."


Maybe
:D

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Edited by John Woods, Aug 02 2018 - 08:45 PM.


#116 Remco Hitman

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Posted Jul 29 2018 - 06:50 AM

Resultant vectors are high school physics. And again, slip angle is not a force as it is measured in degrees, not Newtons.

#117 John Woods

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Posted Jul 29 2018 - 09:54 AM

Focusing on vectors.

The direction of the vector sum is measured in terms of degrees away from a tire longitudinal axis.
But it is not itself a degree or an angle.
It is a vector.

Note in the attached from the Jet Propulsion Laboratory,

"For the front left wheel, the velocity vector v1 at the wheel center is shown. The angle a1 between v1 and the longitudinal axis of the tire is the tire-slip angle, which is defined as positive in the clockwise direction. The positive tire-slip angle shown in the figure generates a positive lateral tire force Fy1. The longitudinal tire force Fx1 is generated by a nonzero longitudinal tire slip. Together, Fx1 and Fy1 make up the tire force vector F1."

From: quora.com/What-are-velocity-vectors
"Velocity is a vector - it has a magnitude and a direction."


:D

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Edited by John Woods, Aug 02 2018 - 08:46 PM.


#118 Michkov

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Posted Jul 29 2018 - 10:59 AM

The misunderstanding here seems to be that the slip angle is the angle between two vectors. In this case the velocity vector of the wheel and the one that is pointing where the wheel is pointing.As Remco is pointing out the angle itself is no vector. But you can compute it from two vectors hence the use of arrows in most diagrams


View PostRemco Hitman, on Jul 27 2018 - 09:23 PM, said:

A slip angle is not a vector as it does not indicate a force. Your image is wrong for oversteer. Both are drawn as understeer by looking at the fronts.

As far as technical/scientific diagrams go. Dont rely on them to be acurate, they are mostly to illustrate concepts rather than how the situation really looks like.

Edited by Michkov, Jul 29 2018 - 11:25 AM.


#119 John Woods

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Posted Jul 29 2018 - 04:32 PM

More interesting stuff from JPL...

"When the road surface is slanted, rather than horizontal, gravity acts on the vehicle in the tangent plane of the road surface, which affects the vehicle velocity. Assume for now that the road surface is horizontal. The dominant forces acting in the plane are the road-tire friction forces; we ignore smaller influences such as wind and air resistance. The road-tire friction forces are algebraic functions of the tire slips, which in turn are algebraic functions of the vehicle velocity. Consequently, measurements of the vehicle accelerations depend algebraically on the vehicle velocities, and the accelerations can therefore be used as indirect measurements of the velocities. In particular, the lateral acceleration ay contains valuable information about the lateral velocity."


Obviously.
:D

Edited by John Woods, Jul 29 2018 - 04:36 PM.


#120 Saiph

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Posted Jul 29 2018 - 06:00 PM

We need someone called Victor on here to explain vectors properly. And someone else called Clarence to make sure the wheels have enough clearance. ;)




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